Why did Tim conclude that all matter is mostly made of empty space?

Which of the following would be an accurate picture of the earth during the summer time of the northern hemisphere?

Displacement is the slope of a velocity vs. time graph a. true b. false

Need what is special about water as a compound? how does water regulate climate? what drives water evaporation?   why is the water vapor fresh water when it rises from the ocean? why might freshwater in the form of snow take longer to enter the water cycle again than liquid precipitation?   what is an aquifer? what role do people play in the water cycle? plz just answer as many as you can ! thx if you !